Mixed adeno-neuroendocrine neoplasm (MiNEN) of the small intestine presenting as sub-occlusive syndrome: a rare and challenging diagnosis
Mouataz Aabalou, Ahmed Jidou Vadel, Anas Derkaoui, Abdelali Guellil, Rachid Jabi, Mohammed BouzianeIntroduction and importance:
Mixed neuroendocrine–non-neuroendocrine neoplasms (MiNENs) are rare gastrointestinal tumors characterized by the coexistence of a neuroendocrine and a non-neuroendocrine component within the same lesion, each representing ≥30% of the tumor volume according to the 2019 WHO classification. Diagnosis remains challenging due to nonspecific symptoms, clinical variability, and limitations of imaging and biopsy sampling. MiNENs of the small intestine are particularly rare, and presentation as subocclusive syndrome is uncommon.
Case presentation:
We report the case of a 72-year-old patient admitted with a three-day history of subocclusive syndrome. Clinical examination revealed a diffusely tender abdomen without peritonitis, and laboratory tests were within normal limits. CT imaging showed an organic small-bowel obstruction upstream of extensive inflammatory-appearing jejunal thickening. Exploratory laparotomy revealed a stenosing jejunal mass located 40 cm from the duodenojejunal flexure, associated with multiple mesenteric lymph nodes. Segmental resection with termino-terminal anastomosis was performed. Histopathology identified a MiNEN composed of a moderately differentiated adenocarcinoma and a neuroendocrine carcinoma, classified as pT3N0Mx, with tumor-free margins.
Clinical discussion:
This case highlights the diagnostic difficulty with MiNENs, which are often mistaken for single-component tumors due to low biopsy sensitivity and the absence of specific radiological features. Diagnosis is most frequently established from surgical specimens. Management relies primarily on complete resection for localized disease, while adjuvant therapy is guided by the most aggressive tumor component.
Conclusion:
The rarity and aggressiveness of MiNENs require a multidisciplinary approach, as well as the publication of additional cases to enhance understanding of their biological behavior and to optimize therapeutic strategies.